CA1265367A

CA1265367A - Expansion dowel assembly

Info

Publication number: CA1265367A
Application number: CA000495673A
Authority: CA
Inventors: Armin Herb
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 1984-11-20
Filing date: 1985-11-19
Publication date: 1990-02-06
Anticipated expiration: 2007-02-06
Also published as: US4669935A; JPS61127909A; DE3442384A1; DE3562155D1; EP0182741B1; JPH065082B2; EP0182741A1

Abstract

ABSTRACT OF THE DISCLOSURE
An expansion dowel assembly is made up of an axially elongated generally cylindrically-shaped dowel body and at least one wedge-shaped expansion member formed monolithically with the dowel body. The dowel body has a first or leading end which is inserted first into a borehole within which the dowel body is to be anchored and an opposite second end. A severable web connects the expansion member to the first end of the dowel body. Before insertion into a borehole, the expansion member projects outwardly from the exterior surface of the dowel body. When the expansion dowel assembly is inserted into a borehole, the web is broken and the expansion member, now separated from the dowel body, is displaced away from the first end within a wedge-shaped recess in the exterior surface of the dowel body. When a load is attached to the trailing end of the dowel body tending to move it opposite to the insertion direction, the expansion member becomes wedged between the borehole surface and the base of the recess in the dowel body.

Description

~Z6536~7 The present invention is directed to an expansion dowel assembly to be anchored in a borehole in a receiving material and is made up of a dowel body and one or a number of wedge-shaped expansion members.
Means for applying a load are located at the trailing end of the dowel body relative to the direction in which.it is inserted into a borehole. ~edge-shaped recesses are formed in the circumferential surface of the dowel body adjacent i-ts leading end for receivin~
the expansion members. The bases o:E th.e recesses are inclined inwardly Erom the leadlng end of the dowel body toward the axis thereoE. Each.o the one or more expansion members is connected by a web to the do~el body and the web is severed or ~roken wh.en the dowel assembly is inserted lnto the borehole.
In a known expansi.on dowel, the dowel b.ody ,`
is rod-shaped and includes a wedge-shaped egpansion member. The wedge-sh.aped e~pansion member is positi.oned within a wedge-shaped recess in the dowel body and is connected with.the dowel body by a s:evera~le web located at the base o~ the reces.s. In a space between the base of the recess and the expansion m~m~er, a severing member is pos-itioned in the form of a trapez.oidally-shaped plate and extends outwardly beyond the circumferential contour of the do~el body. To install this known expansion dowel, it is driven into a borehole and the severing member, because it extends beyond the circumferential surace of the.dowel body and abuts against the surface of t~e borehole, moves against the web and severs it. When the expansion --1-- .

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dowel has reached a sufficient dep-th.in the boreh.ole, the dowel body is pulled opposite to the insertion direction ~y applying a load and the wedge-shaped expansion member anchors the do~el body in the ~orehole.
The need for a severing member for cutting the web has proved to be disadvantageous in such.an expansion dowel, sincè in addition to the e~for-t requi.red to place the dowel there is the pro~lem of correct and secure positioning of the severlng member. Moreover, the severing member, projecting outwardly from th.e dowel body, consi.derably incr0a~es the resistance of the expansion dowel to being inserted into a borehole..
The primary object of the present i.nvent;on :....... is.therefore to provide an expansion dowel asse~bly characterized hy a simple insertion procedure and an ability to lock the dowel body in the borehole. The expansion dowel assem~ly has a simple structure, and does not involve any problems whRn it is p].aced in a borehole~ and does not increase th.e resistance of the assembly to being driven into a boreh.ole.
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In accordance with th.e present invention, : a web holds the expansion member in a position pro-jecting outwardly from the circumferential periphery of the dowel body with.the we~ securing the leading end of the dowel body and the expansion members toyether.
With.the expansion members projecting out-wardly from the circumferenti~l pe.riphery of the dowel body, the expansion members contaat the mouth of the borehole at the commencement oE the insertion : . : . " ~

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procedure. Th.e dri~ing-in force applied to the dowel body causes the webs to ~e broken or severed. With further insertion of the dowel body, recesses in the dowel body present an i.ncreasing depth for -the expansion members which are displaced into the recesses and then are carried along in the i.nsertion direction by th.e dowel body. The expans-ion mem~ers eated within the recesses do not offer any appreciable resistance to the insertion of the assembly into -the. borehole. Sub.~
sequently, when a load is appli.ed to the dowel ~ody acting in th.e direct;on opposi.te to the insertion direction, the expansion members become wedged ~etween the dowel body and the borehole ~urface, anchoring the dowel body in place.
The placement of the webs at the leadin~ ends:
of the dowel body and the expansion members, facili~
tates the insertion of the dowel assembly into a bore-hole with the webs preventing the expans-ion me~.ers from extending forwardly of the dowel body. Further, the webs can be made res:i.stant to bending so that the expansi.on membexs without any addi.tional radial ~upport are maintained in.a position projecting outwardly from.the lateral surface of the dowel body so that the breaking procedure can be efEected. Accordingly, i.t is possible to fabricate the e~pansion dowel ass-em~ly monolithically from a single piece of sheet metal so that material and machi.ning costs are limited. More-over, with a monolithic construction, assem~ly o~
separate dowel parts is not neces-sary as. in kno~n expansion dowel assemblies.

Means are provided on the dowel body for apply.ing a load and such means can be in the Eorm of an external thread at the trailing end of the dowel body.
To prevent any weakening in the cross:-section of the dowel body due to the external threadr the dowel body, preferably formed as a tubular member, is provided in the region of the external thread with inwardly folded parts. Accordingly, reinforcing ribs are formed oriented in the direction of the dowel axis. FurthRr-more, the base of the recesses are inclined i.nwardly rom the leading end of the dowel ~ody. Accordingly, the expansi~n members can be displaced inwardly into the recesses during installation and hefore the weh.
is broken so that the. web serves: as: a pivot point.
Subsequently, as described a~.ove, during initial insertion the webs are broken due to the projection o~ :
-the expansion members from the dowel body. A~ the dowel body is inserted further into the boreh.ole, the expansion members axe carried along with t~e do~el body, in the recesses. I:n this manner th.e expans.ion members are accurately~ guided by the recesses .during the insertion of the expans:ion dowel assembly.
The use of the web. as a bending mem~er is particularly ad~antage.ous in the production of the assembly.: The web is especially suitable as a pi.~ot point for the expansi.on members: with the web.being bent th.rough.approximately 180~
In a preferred em~odiment of the invention three equiangularly spaced recesses and expan~ion members are pro~iaed around the circumfe.ren~ial ~265~67 periphery of the. dowel body s.o that a uni.form di.s~
tribution o~ the anchoring forces is a~forded and high.
anchoring ~alues axe achleved.
The various features of novelty which characterize the invention are pointed aut with.
particularity in the claims annexed to and formi.ng a part oE -this disclosure. For a better understanding of the invetion, its operating advantages and speci.fic objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustra-ted and described p.referred embodiments of the inventlon.
IN THE DRAWINGS
Figure 1 is an elevati.onal ~iew, partly in section, of an expansi.on dowel as.sem~.ly ready to be inserted into a borehole; and Figure. 2 is a sectional view of the expansion dowel assembly sh.own in Figure 1 tak.en along the line II~
The inventi.on is illustrated in the form oE
an expansion dowel assembly 1 made up of a dowel body

2~ wedge-sh.aped expansion members 3 and a web 4 connecting each of the expansion members to the dowel body.
The dowel ~ody 2 is an axially elongated tubular member with a generally cylindrically-sh.aped exterior surface. As viewed in Figure 1, the do~el body has a first or leadi.ng end at the lower end and a second or tra.iling end at the upper end. Thus when the dowel body is inserted into a boreh.ole in a ' ' ~ ,., ~. :

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receiviny material the lower or leading end is inserted first.
The webs 4 connect the first or leading end o~ the dowel body with the expanslon members 3. The expansion members 3 extend from the flrst end toward the second or trailing end. The expansion dowel assembly 1 is formed monolithically from sheet metal as a die punch part. The generally tubular-shaped dowel body 2 has means 5 in the form of an e~ternal thread extendi.ng from its second or trailing end toward th.e first end so th.at a load can be applied to the dowel body.
In th.e region of the dowel body 2 extending from the first end to~ard the second end are three wedge-shaped recesses 6 equiangularly spaced around the.
circumferential periphery of the do~el body, ~:note Figure 2). The base 7 of the wedge-~shaped recesses, is inclined inwardly toward the central axis of the .
dowel body, from th.e first end toward th.e second end.
The axial length of the recess~es represents only a portion of the overall axial length of the dowe.l body.
The webs 4 have a reduc,ed cross-section as.
: compared to th thick.ness, of the remaining dowel body material to facilitate sever~ng or ~reaklng`th.e webs.
wh:en an appxopriate force ls applied at the commence-ment of the dowel body insertion procedure. The expansion members 3 extending Erom the we~s 4 h.a~e a V-shaped cross-sectional sh.ape. InitialIy, as vî.ewed in Figure 4, the expans.ion members 3 project ~utwardly-beyond th.e exterior surface. o the dowel ~ody 2. The V-shape.d expansi.on.members. 3 are complementary~ to the -~,.. .

3~7 V-shaped recesses 6 formed in -the leading end region of the dowel body.
As viewed ln Figure 1, the expansion dowel assembly 1 is ready to be inserted into a borehole, not shown. The expansion members 3 project outwardly beyond the circumferential periphery at khe leading end o~ the dowel body 2. As the dowel assembly is pressed into the borehole, the expansion mem~ers 3 at its leading or first end contact the opening into the borehole and are pivoted inwardly into the rece.sses 6 formed in the dowel body~ ~s the ~owel body is ~orced further into the bo:rehole the webs 4 become severed or broken.
As a result, th.e expansion members 3 are separated from the dowel body and can move relati~e to -the dowel body toward the trailing end of the recesses.
6. Note the phantom lines: in Figure 1 indicatiny the position of the expanslon mem~er moved rearwardly :~
away from the first end o~ th.e dowel ~ody. In the rearward positiont the expansion members 3 project only slightly beyond the circumferential periphery o~ the dowel body 2. With.the dowel body 2 inserted for the deslred depth into the borehole r a load is applied on the exterior thread 5 at the second end of the dowel body. The expansion members 3 remain in position relative to the surface of the borehole while the:
dowel body tends to move in the direction o~posite to the insertion direction, that is, out o~ the borehole. ~s a result, the base. 7 of the recess.es~6 30. inclined relative to the ~xi.s of the dowel ~.ody :moYe " .

relatlve to the expanslon members a.nd press the expansion members radially outwardly agains-t the bore-hole surface so that the expansion dowel assembly 1 becomes anchored with.in the borehole.
The foregoi.ng is a description o~ a preferred embodiment of the invention which is gi~en here by way of example only. Th.e invention is not to be taken as limited to any of the speci:Eic features as describedl but comprehends all such.variations thereof as come within the scope of the appended claims.
An expansion dowel assembly arranged to be anchored in a borehole in a receiving material having an axially elong.ated dowel body having a generally cylindrically-shaped exterior surface with :~
a first end and a second end spaced apart in the axial direction, at least one wedge-shaped expansion member, means for app~.ing a load to said dowel body located in the region of the second end thereof, at least one wedge-shaped recess in the exterior sur-face of said dowel body located adjac nt the first : end thereof for each.said expansion memb.er, said ~ ~:
wedge-shaped recess having a base in¢lined to the axial direction.of said dowel body with.said base converging toward the dowel body axis in the direction from the first end toward the. second end, said at least one expansion member being attached to said dowel body by the attachment means which..are severable when said e~pansion dowel assem~ly l.s inserted into a borehole, wherein the improvement ¢omprises a web , .~, ''~ ' ~6536~

forming the attachment means: of said at least one expansion member to said dowel body so that in thR
attached position before insertion in-to the borehole said e.xpansion member protrudes outwardly from the exterior surface of said dowel body with said web securing said expansi.on member -to said fîrst end of said dowel body.
Wh.ile specific em~odiments of the invention have been shown and described in detail to illustrate the application of the inventIve principles, it will be understood that the invention may~be em~odied otherwise without departing from such.principles.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An expansion dowel assembly arranged to be anchored in a borehole in a receiving material comprises an axially elongated dowel body having a cylindrically shaped exterior surface with a first end and a second end spaced apart in the axial direction, at least one wedge-shaped expansion member having a first end and a second end spaced apart in the axial direction of said dowel body, means for applying a load to said dowel body located in the region of the second end thereof, a wedge-shaped recess in the exterior surface of said dowel body located adjacent the first end thereof for each said expansion member, said wedge-shaped recess has a base inclined to the axial direction of said dowel body with said base converging toward the dowel body axis in the direction from the first end toward the second end, said at least one expansion member being attached to said dowel body with the attachment being severable when said expansion dowel assembly is inserted into a borehole, wherein the improvement comprises a web forming the attachment of said at lest one expansion member to said dowel body so that in the attached position before insertion into the borehole said expansion member protrudes laterally outwardly from the exterior surface of said dowel body adjacent the first end of said dowel body with said web directly attaching the first end of said expansion member to the first end of said dowel body, and said at least one expansion member is formed monolithically with said web and said dowel body, said expansion member being severable, from said dowel body at said web at the first end of said dowel body.

2. An expansion dowel assembly, as set forth in Claim 1, wherein the base of said recesses extend from the exterior surface of said dowel body at the first end thereof inwardly toward the axis of said dowel body in the direction toward the second end thereof.

3. An expansion dowel assembly, as set forth in Claim 1, wherein said web is bendable.

4. An expansion dowel assembly, as set forth in Claim 1, wherein three said recesses are arranged in the exterior surface of said dowel body equiangularly spaced about the dowel body axis, and three expansion members equiangularly spaced around and attached to the first end of said dowel body and each said expansion member arrnged to fit into one of said recesses.

5. An expansion dowel assembly, as set forth in Claim 4, wherein in cross-section extending transveresely of the dowel body axis said recesses and said expansion members are V-shaped.

6. An expansion dowel assembly, as set forth in Claim 4, wherein a separate said web secures each said expansion member to the first end of said dowel body, and said web has a reduced thickness as compared to the thickness of said dowel body so that said web can saver or break when said expansion dowel assembly is inserted into a borehole.

7. An expansion dowel assembly, as set forth in Claim 1, wherein said web is bent approximately through 180 degrees relative to said dowel body at the first end thereof so that said expansion member secured thereto extends from said web toward the second end of said dowel body.